The present invention relates generally to leads for stimulating or monitoring tissue. More particularly, it pertains to a lead having composite tubing.
Leads implanted in or about the heart have been used to reverse certain life threatening arrhythmias, or to stimulate contraction of the heart. Electrical energy is applied to the heart via the leads to return the heart to normal rhythm. Leads have also been used to sense in the atrium or ventricle of the heart and to deliver pacing pulses to the atrium or ventricle.
Cardiac pacing may be performed by the transvenous method or by leads implanted directly onto the epicardium. Permanent transvenous pacing is performed using a lead positioned within one or more chambers of the heart. One or more leads may be positioned in the ventricle or in the atrium through a subclavian vein, and the lead terminal pins are attached to a pacemaker which is implanted subcutaneously.
The lead includes a conductor, such as a coiled conductor, to conduct energy from the pacemaker to the heart, and also signals received from the heart. The lead further includes outer insulation to insulate the conductor. Currently, providing the lead with insulation is done by stringing silicone tubing over the lead. Stringing involves the use of chemicals which swell the silicone tubing, so that the coiled conductor can be pulled through the tubing. As the chemicals evaporate, the tubing contracts around the conductor. Stringing is a complicated manufacturing process which also can result in axial gaps between the conductor and the insulative tubing. The gaps contribute to the outer diameter of the lead.
Accordingly, there is a need for a lead which allows for a less complex manufacturing process and improved insulation. What is also needed is a lead having a smaller outer diameter.
A lead assembly includes a flexible lead body which extends from a proximal end to a distal end, the lead body includes one or more conductors. The lead body includes an outer coating of composite insulative material. The lead assembly further includes an electrode assembly, and the outer coating of composite material is coated directly on at least one conductor.
Several options for the lead assembly are as follows. For instance, in one option, one or more conductors include a first conductor and a second conductor, and at least one coating is coated between the first conductor and the second conductor. In another option, at least one of the conductors comprises a braided conductor. In yet another option, the conductor extends from a first end to a second end and has an intermediate section therebetween, and a portion of the intermediate section has an exposed, non-coated area. The lead assembly, in another option, further includes one or more electrodes electrically coupled with the exposed noncoated area. In another option, the composite coating comprises a first coating and a second coating coated over the first coating.
In another embodiment, a lead assembly includes a flexible lead body which extends from a proximal end to a distal end, the lead body includes one or more conductors, for instance a first conductor and a second conductor. The flexible lead body comprises a first coating disposed directly on a first conductor. The lead assembly further includes an electrode assembly. In addition, at least one second coating of insulative material is coated directly on a second conductor, where the second coating is coated between the first conductor and the second conductor.
Several options for the lead assembly are as follows. For instance, the first conductor, in one option, comprises a braided conductor. In another option, the first conductor extends from a first end to a second end and has an intermediate section therebetween, and a portion of the intermediate section has an exposed, non-coated area, and optionally one or more electrodes are mechanically coupled with the exposed non-coated area. In yet another option, the first conductor comprises a means for extending and retracting the electrode assembly. The lead assembly includes, in another option, a third coating of insulative material coated directly on the first coating of insulative material.
In another embodiment, a lead assembly includes a flexible lead body which extends from a proximal end to a distal end, the lead body includes one or more conductors, where at least one conductor comprises a braided conductor configured to conduct electrical signals. The lead assembly further includes at least one electrode electrically coupled with at least one conductor, and at least one coating of insulation coated directly on the braided conductor.
Several options for the lead assembly are as follows. For instance, in one option, a portion of the at least one coating is removed from the braided conductor to reveal an exposed portion of the braided conductor, and at least one electrode is electrically and mechanically coupled with the exposed portion of the braided conductor. In another option, the braided conductor is rotatable to extend and/or retract at least one electrode. In yet another option, the lead assembly further includes a second coating of insulation coated between the braided conductor and a second conductor, and the second coating is coated directly on the second conductor. Alternatively, the lead assembly further includes an outer coating of composite insulative coating, for example a first coating and a second coating coated directly on the first coating.
In another embodiment, a method comprises providing a first conductor, forming an outer composite lead body over the first conductor, which includes coating composite insulative material directly on a first conductor. The method further includes coupling at least one electrode with the first conductor.
Several options for the method are as follows. For instance, in one option, the method further includes braiding multiple conductors to form the first conductor, and optionally includes rotating the first braided conductor, and extending the at least one electrode. In another option, the method further includes stripping insulative material from a portion of the first conductor, and exposing a portion of the first conductor, and optionally further mechanically and electrically coupling an electrode to the exposed portion of the first conductor. Alternatively, in another option, the method further includes providing a second conductor, and coating a second coating directly on the second conductor.
In another embodiment, a method comprises providing a first conductor for a lead, the first conductor extending from a proximal end to a distal end and having an inner diameter surface and an outer diameter surface. The method further includes coating the outer diameter surface of the first conductor with an insulative coating, including leaving the inner diameter surface uncoated. A second conductor is provided which is coaxial with the first conductor, where the first conductor has a different outer diameter than the second conductor. The method further includes coupling at least one electrode with the first conductor, and coupling the proximal end of the first conductor with an energy source configured to stimulate tissue.
Several options for the method are as follows. For instance, in one option, the method further includes rotating the conductor, and extending the at least one electrode away from the lead. In another option, the method further includes stripping insulative material from a portion of the first conductor, and exposing a portion of the first conductor, and optionally further mechanically and electrically coupling an electrode to the exposed portion of the first conductor. Alternatively, in another option, coating the first conductor includes forming an outer lead body of composite insulative material. In yet another option, the method further includes coating an outer diameter of the second conductor with insulative material.
The lead provides for a smaller lead body diameter due to the elimination of gaps, and tolerance stack-up of the assembly. The lead allows for the ability to start and stop tubing to allow for transition areas of the outer insulation, allowing for the device to have an isodiametric shape. Furthermore, the braided conductors have multiple intersections which offer improved flex fatigue properties. A further benefit is that the anode and cathode are not co-radial, the cathode is suitable for use as a driving mechanism for an extendable or retractable positive fixation lead.
These and other embodiments, aspects, advantages, and features of the present invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art by reference to the following description of the invention and referenced drawings or by practice of the invention. The aspects, advantages, and features of the invention are realized and attained by means of the instrumentalities, procedures, and combinations particularly pointed out in the appended claims and their equivalents.